Various types of surgical procedures are currently performed to investigate, diagnose, and treat diseases of the heart. Such procedures include repair and replacement of mitral, aortic, and other heart valves, repair of atrial and ventricular septal defects, pulmonary thrombectomy, treatment of aneurysms, electrophysiological mapping and ablation of the myocardium, and other procedures in which interventional devices are introduced into the interior of the heart or vessels of the heart.
Of particular interest are intracardiac procedures for surgical treatment of heart valves, especially the mitral and aortic valves. Tens of thousands of patients are diagnosed with aortic and mitral valve disease each year. Various surgical techniques may be used to repair a diseased or damaged valve, including annuloplasty (contracting the valve annulus), quadrangular resection (narrowing the valve leaflets), commissurotomy (cutting the valve commissures to separate the valve leaflets), shortening mitral or tricuspid valve chordae tendonae, reattachment of severed mitral or tricuspid valve chordae tendonae or papillary muscle tissue, and decalcification of valve and annulus tissue. Alternatively, the valve may be replaced by excising the valve leaflets of the natural valve and securing a replacement valve in the valve position, usually by suturing the replacement valve to the natural valve annulus. Various types of replacement valves are in current use, including mechanical and biological prostheses, homografts, and allografts. Valve replacement, however, can present a number of difficulties including that the invasiveness of the procedure can lead to long recovery times and that the irregular shape of the valve annulus can cause difficulty in properly fixing and orienting the replacement valve, which can lead to leaks and other problems. Therefore, in situations where patients can adequately be treating by repairing, rather than replacing, the valve, it is generally preferable to do so.
The mitral and tricuspid valves inside the human heart include an orifice (annulus), two (for the mitral) or three (for the tricuspid) leaflets and a subvalvular apparatus. The subvalvular apparatus includes multiple chordae tendineae, which connect the mobile valve leaflets to muscular structures (papillary muscles) inside the ventricles. Rupture or elongation of the chordae tendineae, commonly known as degenerative mitral valve regurgitation (DMR), results in partial or generalized leaflet prolapse, which causes mitral (or tricuspid) valve regurgitation. Patients can also suffer from functional mitral valve regurgitation (FMR), in which the chordae, leaflets, and papillary muscles are healthy, but the leaflets still do not properly coapt, causing blood to flow back into the atrium. FMR generally results from left ventricular dilation, which displaces the papillary muscles and stretches the valve annulus.
A number of approaches and devices have been employed to treat leaflet prolapse and/or mitral valve regurgitation. One commonly used technique to surgically correct mitral valve regurgitation is the implantation of artificial chordae (usually 4-0 or 5-0 Gore-Tex sutures) between the prolapsing segment of the leaflet of the valve and the papillary muscle. Another technique involves coapting leaflets together with a clip device and/or suture to prevent leaflet prolapse. Other repair devices, such as spacers and balloons, have been used to provide device-assisted leaflet coaptation to prevent mitral valve regurgitation. However, to date, no specific technique for valve repair has achieved general, broad acceptance in the field as the preferred repair method.
Recent cardiac surgery publications acknowledge the improved patient outcomes delivered with mitral valve repair as compared to mitral valve replacement. One of the factors cited for improved outcomes with mitral valve repair is the preservation of the native mitral valve anatomy. While multiple new technologies are being developed, these technologies are directed towards a target patient population that is very high risk having FMR. It would therefore be desirable to provide for improved valve repair that can be used for patients suffering from DMR as well as patients suffering from FMR.